


Ridikulus

by FantasticNumberNine



Series: John Watson and the Prisoner of Azkaban [5]
Category: Harry Potter - J. K. Rowling, Sherlock (TV)
Genre: AU, Bickering, Boggarts, Crossover, Gen, Potterlock, break-ins, cats vs rats, honeydukes chocolates, john introspecting, molly being awesome, more bickering, why
Language: English
Status: Completed
Published: 2015-02-28
Updated: 2015-02-28
Packaged: 2018-03-15 16:39:04
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 1,914
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3454226
Author URL: https://archiveofourown.org/users/FantasticNumberNine/pseuds/FantasticNumberNine
Summary: <blockquote class="userstuff">
              <p>An exciting new Defense class sets a high bar, and hopefully Greg and Mycroft can stop shouting long enough to get John some chocolate from Hogsmeade--he's going to need it.</p>
            </blockquote>





	Ridikulus

**Author's Note:**

> So... Life...
> 
> *diclaimer*

"Five points from Gryffindor because the potion wasn't bollocksed--I swear potions gets worse every year--"

"What'd Moriarty mean? Why would I want revenge on Black?"

Greg stopped abruptly on the stairs, gesturing a bit wildly. "He didn't mean anything, he was just--Oi! How'd you get all the way down there?"

John turned to see Mycroft rushing up the stairs, red in the face and tucking something down his robes.

"Eh, weren't you just with us a second ago?" John blinked, he hadn't thought he'd been that distracted.

"How'd you do that?"

Mycroft tapped his book bag with an air of polite bewilderment. "How did I do what?"

"One minute you were right behind us, the next you were back at the bottom of the stairs again!"

"Ah, well. Yes. I had to go back for something. Nothing, really, I--damn--"

Mycroft's bag split open, spilling a dozen giant books down the stairs. It was unsurprising, but John crouched down to help gather them up as Greg gaped at Mycroft some more.

"Why have you got so many bleeding books?"

"I'm taking more subjects than you, obviously. Here. Be useful and hold these for me."

Mycroft shoved a few books at Greg, who frowned as he looked over the covers. 

"We've just got Defense this afternoon, Myc. You haven't got any of these subjects today."

"Hm, yes," Mycroft fixed his bag and shoved his books inside. "I do hope there's something good for lunch, I'm famished." 

Greg and John watched, puzzled, as he stalked off to the Great Hall.

"D'you get the feeling there's something Myc's not telling us?"

John nodded.

For their first Defense Against the Dark Arts class with Professor Lupin, they took a field trip to the staffroom where Snape appeared to be waiting for them.

"Great, the Greasy Git's here..." Greg muttered.

"I'd rather not witness this." Eyes glittering, Snape strode past the class, turning with a dramatic billow of black robes as he reached the door. "Possibly no one's told you, Lupin, but this class contains Molly Hooper. I would advise you not to entrust her with anything too complicated. Not unless Mister Holmes is there to do it for her."

Molly was scarlet. John glared at Snape, wasn't it enough that he bullied Molly in his own class?

"I was hoping that Molly would assist me with the first stage of the operation, which I'm sure she will do admirably."

Snape left with a sneer, and Professor Lupin ushered Molly and the class towards an old, trembling, wardrobe.

"Can anyone tell us, what is a boggart?"

The class traded cautiously curious looks before Mycroft, with an exaggerated roll of his eyes, raised a hand.

"A boggart is a shape-shifter, seeking to cause fear. So, obviously, it will take the shape of whatever it thinks will frighten us most."

"Excellent, Mister Holmes," Professor Lupin smiled. "The boggart in this wardrobe hasn't yet assumed a form, he doesn't know what will frighten the person outside. No one knows what a boggart looks like when it's alone, but the moment I let him out, he will turn into whatever each of us most fears."

Molly let out a small squeak.

"So we have an advantage over the boggart before we even begin. Care to tell us what it is, John?"

John jerked, not expecting the attention to turn so suddenly to him.

"Er... There's a lot of us, so... It won't know what shape, er, what shape it should be?"

"Precisely. Now, the spell that repels a boggart is quite simple, but it requires force of mind, as the thing that really finishes off a boggart is laughter. Take your fear, and force it into a shape that you find amusing. We'll practice the spell without wands first."

They were each going to get a turn at the boggart. John swallowed. What did he fear most? 

Molly stood, trembling, in front of the wardrobe, her wand out and her face white.

Maybe Voldemort. Voldemort, returned from wherever he was hiding, and at full strength. But how to make boggart-Voldemort funny... And then something worse occurred to John.

The wardrobe opened, and Snape stepped out, glaring menacingly at Molly as he advanced.

"R--r--riddikulus!"

Snape stumbled; suddenly, he was wearing a long, lace-trimmed dress, a giant hat with a moth-eaten vulture and swinging a huge Crimson handbag.

The class roared with laughter and Lupin called Parvati forward.

John lost track of who was facing the boggart. He knew what his boggart would be, but he had no idea how to fight it. How was he supposed to make a Dementor less frightening?

"Greg, you're next!"

John snapped out of his internal panic when several people screamed. 

Greg seemed to freeze in face of the six-foot spider that had appeared in place of Dean's severed hand, then--

"Ridikulus!"

The spider's legs vanished, and it rolled, stopping at John's feet. John raised his wand, unsure of what, exactly, he was going to do, but Lupin jumped between them and the boggart vanished.

Mycroft's arm pointed up, and John followed it to see the silvery-white orb that hung in front of the Professor.

"Molly, forward, let's finish him off!" 

Molly dashed forward, and Snape was back, "Ridikulus!" They had a brief glimpse of Snape in his lacy dress before Molly let out a great "Ha!" of laughter and the boggart exploded.

Class was dismissed and everyone started talking at once, comparing boggarts and congratulating Molly on putting Snape in her grandmother's dress.

"Best Defense lesson we've ever had, hands down!" Greg grinned and they collected their bags.

Mycroft nodded absently, "He seems like a very good teacher."

As the term progressed, Defense continued to be their most interesting class. Care of Magical Creatures was increasingly dull, as Hagrid had them studying flobberworms after Moriarty's incident with Buckbeak. And John was thoroughly through with Divination and Trelawney's increasingly dramatic predictions on his death. 

The return of the Quidditch season was a boon, even if Wood was determined to have them practice in every free moment, desperate to win the Cup before he graduated in June. John returned to the common room after practice one evening in October to find the tower abuzz; the first Hogsmeade weekend had been announced. 

John grunted and dropped down into a chair next to Greg, good mood evaporated. He watched as Crrokshanks jumped up beside Mycroft with a huge spider in his mouth, chewing it slowly all while staring at Greg, who'd turned a bit green.

"Does he have to do that here?" Greg scowled, trying and failing to concentrate on his Astronomy homework.

"Clever Crookshanks, catching spiders so poor Gregory doesn't have to wake the whole Tower screaming. Again--"

"That was one time--"

John yawned and rubbed his eyes. He still had homework to do, and no energy left to do it with.

"Just keep him over there, I've got Scabbers in my bag, sleeping--"

John grabbed his bag and pulled it into his lap, taking out his quill, ink, and parchment. It was going to be a long night.

"Here, copy mine," Greg labeled his last star and pushed his chart towards John.

Mycroft looked like he was about to object, but Crookshanks chose that moment to pounce.

"OI!" Greg roared, trying to wrestle his bag away from Crookshanks, who was ripping at it viciously. "GET OFF, YOU BLOODY BEAST!"

"Gregory, don't hurt him!" Mycroft jumped up as Greg swung his bag around, Crookshanks still clinging to it, hissing and spitting, and then Scabbers came flying out--

"CATCH THAT CAT!"

The whole common room had been watching for a while now, and several people made desperate grabs for the newly freed Crookshanks, including George Lestrade, as the cat chased Scabbers through the crowded common room and crashed to a halt at an old chest of drawers, where Scabbers took refuge and Crookshanks made furious swipes underneath it with his long paws until Mycroft heaved him away.

Greg threw himself onto his stomach and barely managed to pull out a trembling Scabbers by his tail.

"Look at him!" Greg shouted at Mycroft, holding out Scabbers in front of him. "He's skin and bone! You keep that cat away from him!"

"All cats chase rats, Gregory!" Mycroft shouted back. "Crookshanks doesn't understand that it's wrong!"

"There's something off about that animal!" Greg glared at Mycroft as he tried to persuade a frantic Scabbers into his pocket. "It heard me say that Scabbers was in my bag!"

"Rubbish!" Mycroft scoffed. "Crookshanks could smell him, Gregory, he's a cat, how else--"

"Yeah? Your bloody cat's got it in for Scabbers, and Scabbers was here first, and he's ill! So keep your monster the hell away from us!"

Greg stomped through the common room and upstairs to their dormitory. John thumped his head against the arm of his chair, throwing up one hand to stop Mycroft from saying whatever it was he'd been about to say.

Greg and Mycroft weren't speaking. John didn't understand how it was was that while no one was angry with him, it still felt like he was the one being punished in the silent battle of wills between his two best friends. 

On Halloween morning, it finally seemed as though Mycroft and Greg had forgotten their squabble as John pushed his breakfast around his plate morosely.

"We'll bring you sweets back from Honeydukes," Mycroft said, looking unnervingly sorry for him, which only made John feel worse.

"As much as we can carry," Greg added.

"Don't worry about me," John smiled listlessly. "I'll see you at the feast tonight. Have fun."

John wasn't sure how, but he spent most of the afternoon in Professor Lupin's office--which looked reassuringly different from when it had been Lockhart's the previous year. They discussed Divination, and John was able to get the issue of the boggart off his chest just before Snape interrupted with a suspicious looking potion for Lupin.

He was still mulling over Snape's potion when Greg and Mycroft dumped an unseemly amount of chocolate and sweets on his lap in the common room. John told them all about it as they carried the haul up to their dormitory--Greg open mouthed and wide-eyed, Mycroft looking like he'd found an interesting, if not conclusive, puzzle piece.

The Halloween feast was brilliant as ever, though John kept sneaking glances at Lupin.

"Lupin isn't going to drop dead during the Halloween feast, John. Snape is more subtle than that. Let it go," Mycroft said quietly, rolling his eyes at John's foolishness.

There was a crowd outside Gryffindor Tower when John, Greg, and Mycroft arrived after the feast. Trading looks of confusion--a rare treat where Mycroft was involved--they attempted to squeeze to the front to see what the hold-up was.

"Let me through, please," Percy's voice sounded over the crowd as he came bustling through, his sense of self-importance amplified. "You can't have all forgotten the password--excuse me, I'm Head Boy-- Somebody get Professor Dumbledore. Quick."

Sherlock appeared beside Greg, drawing John and Mycroft's attention.

"What's happened?" Greg asked.

"The Fat Lady. She's gone!" Sherlock was almost inappropriately giddy. "Her portrait's been slashed to pieces!"

"What? Who would--why would anyone attack the Fat Lady?"

Mycroft met John's gaze over Sherlock's head, his slightly wide eyes confirming the dread that had settled in John's stomach. 

Peeves's voice floated over Sherlock's excited deductions: "Nasty temper he's got, that's Sirius Black."


End file.
